FIRST TIME SEX POSITION HELP??

I want to have sex with my boyfriend we're both 20, I'm still a virgin but he's not. For some reason my vagina is too tight and we have tried so many times and it couldn't fit. But I know one day it will.

We have been progressing from him fingering me with one finger to two fingers. We will get some lube to help too. I wonder which position is the best for having sex the first time? Help please?